This invention relates to closed circuit personal escape breathing apparatus.
In the event of a fire, a factory accident, a coal mine accident or an oxygen deficiency accident, an antitoxic mask is not effective for protecting the user. To provide a personal breathing apparatus effective under such circumstance, various types of breathing apparatus comprising a self-contained oxygen source have been proposed. Most of them utilize an oxygen bottle or a compressed air bottle as an oxygen source. Although oxygen bottles are more often used because they supply high-purity oxygen gas quite handily and compactly, they must be handled and stored with special care. Also, both oxygen and compressed air bottles are heavy, resulting in a heavy and unnecessarily sturdy overall structure for a self-rescue escape breathing apparatus.
On the other hand, it is also known to use a chemical oxygen generator as a source of oxygen for a personal escape breathing apparatus. Although a chemical oxygen generator is light in weight and easy to store compared to oxygen or compressed air bottles, the overall structure of the breathing apparatus including a carbon dioxide canister, breathing bags, a hood, a mouthpiece, etc., is still heavy and bulky. Most such personal breathing apparatus also require special training for safe use.